DESCRIPTION: The purpose of this investigation is to determine if there is a population of cells in the adult zebrafish that retain the capacity to differentiate into neurons. In Experiment 1, immunohistochemistry (BrdU antib is designed to label newly divided cells in the adult olfactory bulb, and thes cells will be examined for double labeling with neuron-specific antibodies (including Hu, neuron-specific endolase and TUJ1) or glial-specific antibodies (including GFAP). It is hypothesized that at least a subset of newly formed c in the olfactory bulb will be identified as neurons. Experiment 2 is designed determine if the newly generated cells originate in the olfactory bulb itself if they migrate from the telencephalic ventricular zone. The vital dye diI wi be injected into the telencephalic ventricle to label precursor ventricular ce and examination of the distribution of their progeny will be performed after various survival times. It is hypothesized that diI-labeled progeny will appe in the olfactory bulb following an undetermined migration period. The final experiment will attempt to identify the markers for the migratory route from t ventricular zone to the olfactory bulb using immunohistochemical techniques. Antibodies will include PSA-NCAM, GFAP, vimentin and microtubule-associated proteins. It is hypothesized that one or more of these molecules may be invol in forming the route for cell migration.